1. Field of the Invention
The present invention relates to a lens-fitted photo film unit. More particularly, the present invention relates to a lens-fitted photo film unit from which a photo film cassette can be safely removed after taking exposures.
2. Description Related to the Prior Art
There is a lens-fitted photo film unit including a simply constructed exposure-taking mechanism and pre-loaded with a photo film cassette, which contains photo film of the 135 type. The lens-fitted photo film unit has a cassette containing chamber and a photo film roll chamber. The cassette containing chamber contains a cassette shell of the photo film cassette. The photo film roll chamber contains a roll form into which the photo film is externally wound after being drawn from the cassette shell. The lens-fitted photo film unit is characteristically easy to handle and convenient even for amateurs who are unfamiliar to photography.
In the lens-fitted photo film unit, a photo film winder wheel is manually rotated each time after taking one exposure. A spool in the cassette shell is caused to rotate in a direction of winding the photo film, to wind the photo film by one frame. The use of the lens-fitted photo film unit is finished when all the photo film is wound into the cassette shell. The lens-fitted photo film unit then forwarded to a photo laboratory.
In the photo laboratory, the lens-fitted photo film unit is oriented upside down for processing. A bottom lid disposed on the bottom of the cassette containing chamber is opened forcibly to open a bottom opening which provides access to the a photo film chamber. Then the orientation of the lens-fitted photo film unit is changed again to direct its bottom downwards. The lens-fitted photo film unit is shaken up and down strongly to eject the photo film cassette from the cassette containing chamber.
There is a lens-fitted photo film unit in which a photo film cassette of the IX 240 type is contained. The IX 240 type includes a resin cassette shell, and incorporates a cassette shutter, disposed in a photo film passageway, and rotatable between an open position for opening the photo film passageway and a closed position for closing the photo film passageway. In the lens-fitted photo film unit, the cassette shutter is rotated to the closed position in response to an opening movement of the bottom lid, preventing ambient light from entering the cassette shell of the photo film removed from the lens-fitted photo film unit after exposure have been made.
However, there is a problem in that the change in orientation of the lens-fitted photo film unit is required in removing the photo film cassette, so that efficiency in the operation decreases. If an operator fails to catch the photo film cassette which ejected upon shaking the lens-fitted photo film unit, the photo film cassette may forcefully strike a hard surface and be damaged.
In the photo film cassette where the cassette shell of resin contains the cassette shutter, shock of drop of the photo film cassette is likely to open the cassette shutter to cause entry of ambient light into the cassette shell, thereby fogging the photo film. Also an outer shape of the cassette shell is likely to be damaged.